Answer: A general guideline is to determine the mature size of the plant and how much space it would take. There are many different varieties of lavender, some more compact than others, but assume that a plant takes about two square feet of space. You'd need 800 plants. Another important factor with lavender is that it is more difficult to start from seed than many other plants. It has a germination factor of about 50-65%. So, you're back to 1600 seeds! You might want to "overseed" to increase the likelihood of filling in your space, and then thin extra seedlings. You could pot them up if you didn't want to waste them.
Finally, the Arizona Herb Association is an active garden club in your area. For more info on club activities, call 602-470-8086, ext. 830. I hope this info helps, and good luck with your project!
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